Babaeenezhad Esmaeel, Moradi Sarabi Mostafa, Rajabibazl Masoumeh, Oraee-Yazdani Saeed, Karima Saeed
Department of Clinical Biochemistry, School of Medicine, Student Research Committee, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Nutritional Health Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran.
Mol Biol Rep. 2023 Jan;50(1):589-597. doi: 10.1007/s11033-022-08051-3. Epub 2022 Nov 10.
The relationship between peroxisome proliferator-activated receptor gamma (PPARγ) expression level and epigenetic modifications occurring in glioblastoma multiforme (GBM) pathogenesis is largely unknown. Herein, we examine the association of PPARγ expression with its promoter and genomic global DNA methylation status, as well as DNA methyltransferases (DNMTs) gene expression in GBM patients.
We examined the patterns of promoter methylation and PPARγ expression in 26 GBM tissues and 13 adjacent non-tumor tissues by methylation-specific PCR (MSP), real-time PCR, and ELISA, respectively. Also, we examined the genomic global 5-methyl cytosine levels and DNMTs gene expression using ELISA and real-time PCR methods, respectively.
We found that hypermethylation on a specific region of the PPARγ promoter is significantly associated with the downregulation of the PPARγ gene and protein level in GBM patients. Interestingly, the amount of 5-methyl cytosine level was significantly reduced in GBM patients and positively correlated with PPARγ protein expression. Furthermore, the expression level of DNMT1, DNMT3A, and 3B were upregulated in GBM patients and the average expression level of all three DNMTs was positively correlated with tumor area. Also, we found that tumors from cortical regions exhibited a higher global DNA hypomethylation and PPARγ hypermethylation was related to the increase in GBM risk.
Our study demonstrated that global DNA methylation and PPARγ epigenetic silencing is associated with the GBM risk. Our data provide a novel molecular mechanistic insight into epigenetic silencing of PPARγ in GBM patients that may be relevant as a key tumor marker for GBM pathogenesis.
在多形性胶质母细胞瘤（GBM）发病机制中，过氧化物酶体增殖物激活受体γ（PPARγ）表达水平与表观遗传修饰之间的关系在很大程度上尚不清楚。在此，我们研究GBM患者中PPARγ表达与其启动子和基因组整体DNA甲基化状态以及DNA甲基转移酶（DNMTs）基因表达的关联。
我们分别通过甲基化特异性PCR（MSP）、实时PCR和ELISA检测了26例GBM组织和13例相邻非肿瘤组织中启动子甲基化模式和PPARγ表达。此外，我们分别使用ELISA和实时PCR方法检测了基因组整体5-甲基胞嘧啶水平和DNMTs基因表达。
我们发现GBM患者中PPARγ启动子特定区域的高甲基化与PPARγ基因和蛋白水平的下调显著相关。有趣的是，GBM患者中5-甲基胞嘧啶水平显著降低，且与PPARγ蛋白表达呈正相关。此外，GBM患者中DNMT1、DNMT3A和3B的表达水平上调，且所有三种DNMTs的平均表达水平与肿瘤面积呈正相关。我们还发现，来自皮质区域的肿瘤表现出更高的整体DNA低甲基化，且PPARγ高甲基化与GBM风险增加有关。
我们的研究表明，整体DNA甲基化和PPARγ表观遗传沉默与GBM风险相关。我们的数据为GBM患者中PPARγ表观遗传沉默提供了新的分子机制见解，这可能作为GBM发病机制的关键肿瘤标志物具有相关性。
